KR102408630B1 - Epoxy resins, epoxy resin compositions, cured epoxy resins, and composite materials - Google Patents

Abstract

An epoxy resin comprising an epoxy compound A having two or more mesogen structures and one or more phenylene groups, and an epoxy compound B having two or more mesogen structures and one or more divalent biphenyl groups.

Description

Epoxy resins, epoxy resin compositions, cured epoxy resins, and composite materials

The present invention relates to an epoxy resin, an epoxy resin composition, a cured epoxy resin material, and a composite material.

Epoxy resins are widely used as matrix resins of fiber-reinforced plastics (FRP). In recent years, an epoxy resin is also used as a matrix resin for FRP used for aerospace applications requiring high levels of various physical properties such as fracture toughness, elasticity, and heat resistance. However, while thermosetting resins, such as an epoxy resin, are excellent in heat resistance compared with a thermoplastic resin, there exists a tendency inferior to fracture toughness.

As a method of improving the fracture toughness of an epoxy resin, it is known, for example to introduce a mesogen structure into a molecule|numerator and to improve the orientation of a molecule|numerator in a hardened|cured material.

An epoxy resin having a mesogenic structure in a molecule (hereinafter also referred to as a mesogen-containing epoxy resin) generally has strong crystallinity and a high viscosity as compared with other epoxy resins. For this reason, sufficient fluidity|liquidity may not be obtained at the time of an operation|work. Accordingly, as a method of improving the fluidity of the mesogen-containing epoxy resin, a technique has been proposed in which an epoxy monomer having a mesogenic structure and a divalent phenol compound are reacted to form an epoxy compound with a molecular weight within a specific range (for example, , see Patent Document 1).

On the other hand, it has been reported that when liquid crystalline polyester is injection molded in a liquid crystal state, molecules are aligned in a fixed direction by shear flow in the mold (for example, refer to Non-Patent Document 1).

International Publication No. 2016-104772

Yoshihara et al., Polymer Preprints, Japan, 61(1), 625(2012)

The mesogen-containing epoxy resin described in Patent Document 1 has achieved a decrease in softening point, but still has strong crystallinity and high viscosity under the temperature conditions at the time of operation. There is room for improvement in

In addition, although it is possible to achieve low viscosity under the temperature conditions at the time of operation, the possibility that the viscosity may rise due to other factors (for example, orientation of molecules due to shear flow of the resin reported in Non-Patent Document 1) is also considered. There is a need.

In view of the above situation, an object of the present invention is to provide an epoxy resin and an epoxy resin composition excellent in viscosity stability during operation, and a cured epoxy resin product and a composite material obtained using these resins.

Means for solving the above problems include the following embodiments.

<1> An epoxy resin comprising an epoxy compound A having two or more mesogenic structures and one or more phenylene groups, and an epoxy compound B having two or more mesogenic structures and one or more divalent biphenyl groups.

<2> At least one of the epoxy compound A and the epoxy compound B has a structure in which one phenylene group or the divalent biphenyl group is disposed between the two mesogenic structures, in <1> Epoxy resins described.

<3> <1> or <2>, wherein at least one of the two or more mesogenic structures that at least one of the epoxy compound A and the epoxy compound B has is a mesogenic structure represented by the following general formula (3) The epoxy resin described in.

(In general formula (3), R ³ to R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)

<4> The epoxy resin composition containing the epoxy resin in any one of <1>-<3>, and a hardening|curing agent.

<5> The epoxy resin composition according to <4>, wherein a smectic structure can be formed when cured.

<6> A cured epoxy resin product, which is a cured product of the epoxy resin composition according to <4> or <5>.

<7> A composite material comprising the cured epoxy resin according to <6> and a reinforcing material.

ADVANTAGE OF THE INVENTION According to this invention, the epoxy resin and epoxy resin composition excellent in the viscosity stability at the time of operation, and the epoxy resin hardened|cured material and composite material obtained using these are provided.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated in detail. However, this invention is not limited to the following embodiment. In the following embodiments, the constituent elements (including element steps and the like) are not essential except as otherwise specified. The same applies to numerical values and ranges, and the present invention is not limited.

In the present disclosure, the word "process" includes not only a process independent from other processes, but also a process that cannot be clearly distinguished from other processes if the purpose of the process is achieved.

In the present disclosure, in the numerical range indicated using "-", the numerical values described before and after "-" are included as the minimum value and the maximum value, respectively.

In the numerical range described in steps in the present disclosure, the upper limit or lower limit described in one numerical range may be substituted with the upper limit or lower limit of the numerical range described in another step. In addition, in the numerical range described in this indication, you may substitute the upper limit or lower limit of the numerical range with the value shown in an Example.

In the present disclosure, each component may contain a plurality of types of the corresponding substance. When a plurality of types of substances corresponding to each component exist in the composition, the content or content of each component means the total content or content of the plurality of types of substances present in the composition, unless otherwise specified.

In this indication, the particle|grains corresponding to each component may contain multiple types. When a plurality of types of particles corresponding to each component exist in the composition, the particle diameter of each component means a value for a mixture of particles of the plurality of types present in the composition, unless otherwise specified.

In this specification, "epoxy compound" means the compound which has an epoxy group in a molecule|numerator. An "epoxy resin" is a concept to grasp|ascertain a some epoxy compound as an aggregate|assembly, and means that it is a state which is not hardened|cured.

<Epoxy resin>

The epoxy resin of the present disclosure includes an epoxy compound A having two or more mesogenic structures and one or more phenylene groups, and an epoxy compound B having two or more mesogenic structures and one or more divalent biphenyl groups.

In the present disclosure, when two or more mesogenic structures of the epoxy compound A include a phenylene group, the phenylene group is different from “one or more phenylene groups”. When the 2 or more mesogenic structure which the epoxy compound B has contains a bivalent biphenyl group, let the said bivalent biphenyl group be different from "one or more divalent biphenyl groups."

The number of epoxy compound A and the epoxy compound B contained in an epoxy resin may be one, respectively, or 2 or more types may be sufficient as them. In addition, the mesogenic structure which the epoxy compound A and the epoxy compound B have may be same or different.

By the examination of the present inventors, the epoxy resin containing the epoxy compound B is more than the epoxy resin containing the compound (epoxy compound A) obtained by making the epoxy monomer which has a mesogenic structure described in patent document 1 and a divalent phenol compound react , it was found that the viscosity tends to decrease when the temperature is raised and the handleability is excellent. That is, the epoxy compound A having a phenylene group in the molecule, as a single entity, has a smectic liquid crystal phase at the temperature at the time of operation (for example, 100° C. or less), whereas the epoxy compound having a biphenyl group in the molecule Compound B is a nematic liquid crystal phase or an isotropic phase in all temperature ranges from normal temperature (25 degreeC) to 150 degreeC as its single-piece|unit. This is considered to be because the biphenyl group in the molecule of the epoxy compound B has a larger molecular weight than the phenylene group, so that the molecular alignment property is lowered and it does not have a smectic liquid crystal phase that is a higher-order structure. For this reason, it is considered that the epoxy resin containing the epoxy compound B has a lower viscosity under the temperature conditions at the time of operation than the epoxy resin containing the epoxy compound A, and tends to be excellent in fluidity.

In addition, it was found that the epoxy resin containing both the epoxy compound A and the epoxy compound B has excellent viscosity stability under a situation in which a shear stress is continuously applied as compared to the epoxy resin containing only the epoxy compound B. It is believed that this is because the epoxy compound B having a biphenyl group in the molecule has a property that the molecules are easily oriented due to a physical stimulus such as a shear stress, compared to the epoxy compound A having a phenylene group in the molecule. For this reason, for example, when an epoxy resin is mixed with a hardening|curing agent, it is thought that a viscosity increase becomes more likely to occur because a shear stress is continuously applied to an epoxy resin.

By including both the epoxy compound A and the epoxy compound B, the epoxy resin of the present disclosure is compatible with lowering the viscosity in the temperature range during operation and viscosity stability under a situation in which a shear stress is continuously applied.

The ratio of the mass basis of the epoxy compound A and the epoxy compound B in an epoxy resin is not specifically limited. From the viewpoint of achieving both low viscosity in the temperature range during operation and viscosity stability under continuous application of shear stress, the ratio of epoxy compound A to epoxy compound B (epoxy compound A: epoxy compound B) is 1:9 It is preferable that it is -9:1, it is more preferable that it is 3:7-9:1, It is still more preferable that it is 4:6-8:2, It is especially preferable that it is 6:4-8:2.

The epoxy resin may contain epoxy compounds other than the epoxy compound A and the epoxy compound B. For example, you may contain the mesogen-epoxy monomer mentioned later.

When the epoxy resin contains epoxy compounds other than the epoxy compound A and the epoxy compound B, the total content of the epoxy compound A and the epoxy compound B is not particularly limited. For example, it is preferable that they are 70 mass % - 99 mass % of the whole epoxy resin, It is more preferable that they are 80 mass % - 99 mass %, It is still more preferable that they are 90 mass % - 99 mass %.

(specific epoxy compounds)

The structure of the epoxy compound A and the epoxy compound B (hereinafter, collectively referred to as a specific epoxy compound) is not particularly limited as long as it has two or more mesogenic structures and one or more phenylene groups or divalent biphenyl groups. .

The two or more mesogenic structures contained in 1 molecule of a specific epoxy compound may differ and may be same.

The mesogenic structure which a specific epoxy compound has means the structure in which the epoxy resin containing the epoxy compound which has this may express liquid crystallinity. Specifically, biphenyl structure, phenylbenzoate structure, cyclohexylbenzoate structure, azobenzene structure, stilbene structure, terphenyl structure, anthracene structure, derivatives thereof, two or more of these mesogenic structures are bonded through a bonding group structure and the like.

The epoxy resin containing the epoxy compound which has a mesogenic structure forms a higher order structure in hardened|cured material. Here, the higher-order structure means a structure including a higher-order structure in which the components are arranged to form a micro-ordered structure, and for example, a crystal phase and a liquid crystal phase correspond. The presence or absence of such a higher-order structure can be judged by a polarization microscope. That is, in observation in a cross nicol state, it can be discriminated by observing an interference fringe due to depolarization. This higher-order structure usually exists as an island in the cured product of the epoxy resin composition to form a domain structure, and one island corresponds to one higher-order structure. The component itself of this higher-order structure is generally formed by a covalent bond.

Examples of the higher-order structure formed in a cured state include a nematic structure and a smectic structure. The nematic structure and the smectic structure are each a kind of liquid crystal structure. The nematic structure is a liquid crystal structure in which long molecular axes are oriented in the same direction and only have an alignment order. In contrast, the smectic structure has a one-dimensional positional order in addition to the alignment order, and is a liquid crystal structure having a layered structure. The orderliness is higher in the smectic structure than in the nematic structure. Therefore, it is more preferable to form a higher-order structure of the smectic structure from the viewpoint of thermal conductivity and fracture toughness of the cured product.

Whether or not a smectic structure is formed in the cured product of the epoxy resin can be determined by X-ray diffraction measurement of the cured product. The X-ray diffraction measurement can be performed using, for example, an X-ray diffraction apparatus manufactured by Sharikaku Co., Ltd. When a CuKα1 line is used and a tube voltage of 40 kV, a tube current of 20 mA, is measured in the range of 2θ = 2° to 0°, a diffraction peak appears in the range of 2θ = 2° to 0° in the case of a cured product having a smectic structure.

The structure represented by the following general formula (1) may be sufficient as the mesogenic structure which a specific epoxy compound has.

In general formula (1), X represents at least 1 sort(s) of coupling group selected from the group (A) which consists of a single bond or the following divalent group. Y each independently represents an aliphatic hydrocarbon group having 1 to 8 carbon atoms, an aliphatic alkoxy group having 1 to 8 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, or an acetyl group. n each independently represents the integer of 0-4.

In group (A), each Y is independently an aliphatic hydrocarbon group having 1 to 8 carbon atoms, an aliphatic alkoxy group having 1 to 8 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, or an acetyl group. represents the flag. n each independently represents the integer of 0-4, k represents the integer of 0-7, m represents the integer of 0-8, and 1 represents the integer of 0-12.

In the mesogenic structure represented by the general formula (1), when X is at least one linking group selected from the group (A) consisting of the divalent group, at least one selected from the group (Aa) consisting of the following divalent group It is preferable that it is a linking group of a species, and it is more preferable that it is at least 1 type of linking group selected from group (Aa), and it is a linking group containing at least 1 cyclic structure.

In group (Aa), each Y is independently an aliphatic hydrocarbon group having 1 to 8 carbon atoms, an aliphatic alkoxy group having 1 to 8 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a cyano group, a nitro group, or an acetyl group. represents the flag. n each independently represents the integer of 0-4, k represents the integer of 0-7, m represents the integer of 0-8, and 1 represents the integer of 0-12.

Among the two or more mesogenic structures that at least one of the epoxy compound A and the epoxy compound B has, at least one is preferably a mesogenic structure represented by the following general formula (2), and all are represented by the following general formula (2) It is more preferable that it is the mesogenic structure used.

In the general formula (2), the definitions and preferred examples of X, Y and n are the same as the definitions and preferred examples of X, Y and n in the general formula (1).

In addition, it is preferable that at least one of the two or more mesogenic structures which at least one of the epoxy compound A and the epoxy compound B has is a mesogenic structure represented by the following general formula (3), and all are the following general formula (3) It is more preferable that it is a mesogenic structure represented by

In the general formula (3), R ³ to R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.

R ³ to R ⁶ are each independently preferably a hydrogen atom or an alkyl group having 1 to 2 carbon atoms, more preferably a hydrogen atom or a methyl group, still more preferably a hydrogen atom. Moreover, it is preferable that 2-4 of R< ³ >-R< ⁶ > are a hydrogen atom, It is more preferable that 3 or 4 are a hydrogen atom, It is still more preferable that all four are a hydrogen atom. When any one of R ³ to R ⁶ is an alkyl group having 1 to 3 carbon atoms, it is preferable that at least one of R ³ and R ⁶ is an alkyl group having 1 to 3 carbon atoms.

When a specific epoxy compound is an epoxy compound A, the structure represented by the following general formula (5A) is mentioned as a phenylene group which the epoxy compound A has. When a specific epoxy compound is an epoxy compound B, the structure represented by the following general formula (5B) is mentioned as a bivalent biphenyl group which epoxy compound B has.

In the general formulas (5A) and (5B), * represents a bonding position with an adjacent atom. Examples of the adjacent atoms include an oxygen atom and a nitrogen atom. R ¹ and R ² each independently represent an alkyl group having 1 to 8 carbon atoms. m each independently represents the integer of 0-4.

R ¹ and R ² each independently represent an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 3 carbon atoms, more preferably a methyl group.

m is each independently, it is preferable that it is an integer of 0-2, It is more preferable that it is an integer of 0-1, It is still more preferable that it is 0.

Among the structures represented by the general formula (5A), the structures represented by the following general formulas (5a) are preferable, and among the structures represented by the general formulas (5B), the structures represented by the following general formulas (5b) are preferable. A specific epoxy compound having such a structure tends to have a linear molecular structure. For this reason, the stacking property of a molecule|numerator is high, and it is considered that it is easy to form a higher order structure.

In the general formulas (5a) and (5b), the definitions and preferred examples of *, R ¹ , R ² and m are *, R ¹ , R ² and It is the same as the definition and preferred examples of m.

It is preferable that a specific epoxy compound has the structure of the state in which one phenylene group or a bivalent biphenyl group was arrange|positioned between two structures represented by General formula (1). The specific aspect of "the state in which one phenylene group or a bivalent biphenyl group was arrange|positioned between two structures represented by General formula (1)" which a specific epoxy compound has is not specifically limited. For example, the epoxy group of the compound having a mesogenic structure and an epoxy group, and the functional group of the compound having a phenylene group or a biphenyl group and a functional group capable of reacting with an epoxy group may be reacted.

The specific epoxy compound may be an epoxy compound which has a structure represented by the following general formula (1-A) or general formula (1-B).

In the general formulas (1-A) and (1-B), the definitions and preferred examples of X, Y and n are the same as the definitions and preferred examples of X, Y and n in the general formula (1). In addition, the definitions and preferred examples of R ¹ , R ² , and m are the same as the definitions and preferred examples of R ¹ , R ² and m in the general formulas (5A) and (5B). Z each independently represents -O- or -NH-.

That is, in the general formulas (1-A) and (1-B), the benzene ring to which R ¹ or R ² is assigned preferably has 2 to 4 hydrogen atoms, and 3 or 4 hydrogen atoms It is more preferable to have, and it is still more preferable to have 4 hydrogen atoms.

From the viewpoint of higher-order structure formation, the epoxy compound having a structure represented by the general formula (1-A) is preferably an epoxy compound having a structure represented by the following general formula (2-A), and the general formula (1-A) It is preferable that the epoxy compound which has a structure represented by B) is an epoxy compound which has a structure represented by the following general formula (2-B).

In the general formulas (2-A) and (2-B), the definitions and preferred examples of X, Y, n, m, R ¹ , R ² and Z are the general formulas (1-A) and the general formulas (2-B) It is the same as the definitions and preferred examples of X, Y, n, m, R ¹ , R ² and Z in (1-B).

As the epoxy compound having a structure represented by the general formula (1-A), an epoxy having at least one structure selected from the group consisting of the following general formulas (3-A-1) and (3-A-2) compounds are exemplified.

As the epoxy compound having a structure represented by the general formula (1-B), an epoxy having at least one structure selected from the group consisting of the following general formulas (3-B-1) and (3-B-2) compounds are exemplified.

In the general formula (3-A-1), general formula (3-A-2), general formula (3-B-1) and general formula (3-B-2), the definitions of R ³ to R ⁶ and Preferred examples are the same as the definitions and preferred examples of R ³ to R ⁶ in the general formula (3). In addition, the definitions and preferred examples of R ¹ , R ² , m and Z are the same as the definitions and preferred examples of R ¹ , R ² , m and Z in the general formulas (1-A) and (1-B). do.

The number of structures represented by General formula (1) in a specific epoxy compound will not be specifically limited if it is two or more. It is preferable that at least one part of specific epoxy compounds is a compound (dimer compound) containing two structures represented by General formula (1) from a viewpoint of reducing the viscosity at the time of work.

As a structure in case a specific epoxy compound is a dimer compound, the compound represented by the following general formula (4-A-1) or the following general formula (4-B-1) is mentioned.

In the general formula (4-A-1) or (4-B-1), the definitions and preferred examples of X, Y, n, m, R ¹ , R ² and Z are in the general formula (1-A) ) and the definitions and preferred examples of X, Y, n, m, R ¹ , R ² and Z in the general formula (1-B).

From the viewpoint of forming a higher-order structure, the epoxy compound having a structure represented by the general formula (4-A-1) is preferably an epoxy compound having a structure represented by the following general formula (5-A-1), and the general It is preferable that the epoxy compound which has a structure represented by Formula (5-B-1) is an epoxy compound which has a structure represented by the following general formula (5-B-1).

In the general formulas (5-A-1) and (5-B-1), the definitions and preferred examples of X, Y, n, m, R ¹ , R ² and Z are in the general formula (4-A) -1) and the definitions and preferred examples of X, Y, n, m, R ¹ , R ² and Z in the general formula (4-B-1).

As a specific example of the epoxy compound which has a structure represented by general formula (4-A-1), the epoxy compound which has a structure represented by the following general formula (6-A-1) - general formula (6-A-3) can be heard

As a specific example of the epoxy compound which has a structure represented by general formula (4-B-1), the epoxy compound which has a structure represented by the following general formula (6-B-1) - general formula (6-B-3) can be heard

In the formulas (6-A-1) to (6-A-3) and (6-B-1) to (6-B-3), R ³ to R ⁶ , R ¹ , R ² , m and Z are definitions and preferred examples of general formula (3-A-1), general formula (3-A-2), general formula (3-B-1) or general formula (3-B) It is the same as the definitions and preferred examples of R ³ to R ⁶ , R ¹ , R ² , m and Z in -2).

(Synthesis method of specific epoxy compound)

The method of synthesize|combining a specific epoxy compound is not specifically limited. For example, a compound having a mesogenic structure and an epoxy group (hereinafter also referred to as a mesogenic epoxy monomer) may be reacted with an aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer.

The mesogenic epoxy monomer may be a compound which has a structure represented by the following general formula (1-m).

In the general formula (1-m), the definitions and preferred examples of X, Y and n are the same as the definitions and preferred examples of X, Y and n in the general formula (1) described above.

From the viewpoint of forming a higher-order structure, the mesogenic epoxy monomer represented by the general formula (1-m) is preferably a mesogenic epoxy monomer having a structure represented by the following general formula (2-m).

In the general formula (2-m), the definitions and preferred examples of X, Y and n are the same as the definitions and preferred examples of X, Y and n in the general formula (1-m).

As for the mesogenic epoxy monomer represented by general formula (1-m), it is more preferable that it is a mesogenic epoxy monomer which has a structure represented by the following general formula (3-m).

In the general formula (3-m), the definitions and preferred examples of R ³ to R ⁶ are the same as the definitions and preferred examples of R ³ to R ⁶ in the general formula (3).

The method for synthesizing a specific epoxy compound by reacting a mesogenic epoxy monomer with an aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer is not particularly limited. Specifically, for example, by dissolving, for example, a mesogenic epoxy monomer, an aromatic compound having a functional group capable of reacting with the epoxy group dgj of the mesogenic epoxy monomer, and a reaction catalyst to be used in a solvent, and stirring while heating, A specific epoxy compound can be synthesized.

Alternatively, for example, the mesogenic epoxy monomer and the aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer are mixed without using a reaction catalyst and solvent used as needed, and stirred while heating. , a specific epoxy compound can be synthesized.

The solvent is particularly limited as long as it is a solvent capable of dissolving the mesogenic epoxy monomer and an aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer and heating to a temperature required for both compounds to react. doesn't happen Specific examples include cyclohexanone, cyclopentanone, ethyl lactate, propylene glycol monomethyl ether, N-methylpyrrolidone, methyl cellosolve, ethyl cellosolve, and propylene glycol monopropyl ether.

The amount of the solvent is not particularly limited as long as it can dissolve the mesogenic epoxy monomer, the aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer, and, if necessary, the reaction catalyst to be used at the reaction temperature. . The solubility differs depending on the type of raw material before the reaction, the type of solvent, etc., but, for example, if the solid content concentration to be charged is 20 to 60 mass%, the viscosity of the solution after the reaction tends to be in a preferable range. .

The kind of aromatic compound which has a functional group which can react with the epoxy group of a mesogenic epoxy monomer is not specifically limited. From the viewpoint of forming a smectic structure in the cured product, a dihydroxybenzene compound having a structure in which two hydroxyl groups are bonded to one benzene ring, a diaminobenzene compound having a structure in which two amino groups are bonded to one benzene ring, ratio A dihydroxybiphenyl compound having a structure in which one hydroxyl group is bonded to two benzene rings forming a phenyl structure, and diaminobiphenyl having a structure in which one amino group is bonded to two benzene rings forming a biphenyl structure It is preferable that it is at least 1 sort(s) (it is also called a specific aromatic compound hereafter) selected from the group which consists of compounds.

Examples of the dihydroxybenzene compound include catechol, resorcinol, hydroquinone, and derivatives thereof.

Examples of the diaminobenzene compound include 1,2-diaminobenzene, 1,3-diaminobenzene, 1,4-diaminobenzene, and derivatives thereof.

As the dihydroxybiphenyl compound, 2,2'-dihydroxybiphenyl, 2,3'-dihydroxybiphenyl, 2,4'-dihydroxybiphenyl, 3,3'-dihydroxybi phenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, derivatives thereof, and the like can be exemplified.

Examples of the diaminobiphenyl compound include 2,2'-diaminobiphenyl, 2,3'-diaminobiphenyl, 2,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,4 '-diaminobiphenyl, 4,4'-diaminobiphenyl, derivatives thereof, and the like can be exemplified.

As a derivative of a specific aromatic compound, the compound which the benzene ring of the specific aromatic compound couple|bonded with substituents, such as a C1-C8 alkyl group, is mentioned. A specific aromatic compound may be used individually by 1 type, and may use 2 or more types together.

The type of the reaction catalyst is not particularly limited, and an appropriate one can be selected from the viewpoint of reaction rate, reaction temperature, storage stability, and the like. Specifically, an imidazole compound, an organophosphorus compound, a tertiary amine, a quaternary ammonium salt, etc. are mentioned. A reaction catalyst may be used individually by 1 type, and may use 2 or more types together.

From a viewpoint of the heat resistance of hardened|cured material, as a reaction catalyst, an organophosphorus compound is preferable.

Preferred examples of the organophosphorus compound include an organic phosphine compound, a compound having intramolecular polarization formed by adding a compound having a π bond such as maleic anhydride, a quinone compound, a diazophenylmethane, and a phenol resin to an organic phosphine compound; The complex of a phosphine compound and an organoboron compound, etc. are mentioned.

Specific examples of the organic phosphine compound include triphenylphosphine, diphenyl(p-tolylphosphine, tris(alkylphenyl)phosphine, tris(alkoxyphenyl)phosphine, tris(alkylalkoxyphenyl)phosphine, tris( Dialkylphenyl)phosphine, tris(trialkylphenyl)phosphine, tris(tetraalkylphenyl)phosphine, tris(dialkoxyphenyl)phosphine, tris(trialkoxyphenyl)phosphine, tris(tetraalkoxyphenyl)phosphine fins, trialkylphosphines, dialkylarylphosphines, alkyldiarylphosphines and the like.

Specifically as the quinone compound, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethone oxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy-1,4-benzoquinone, phenyl-1,4-benzoquinone and the like.

Specific examples of the organoboron compound include tetraphenylborate, tetra-p-tolylborate, and tetra-n-butylborate.

The amount of the reaction catalyst is not particularly limited. From the viewpoint of reaction rate and storage stability, it is preferable that the amount is 0.1 parts by mass to 1.5 parts by mass relative to 100 parts by mass of the total mass of the mesogenic epoxy monomer and the aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer. And it is more preferable that it is 0.2 mass part - 1 mass part.

When synthesizing a specific epoxy compound using a mesogenic epoxy monomer, all of the mesogenic epoxy monomer may react to form a specific epoxy compound, and a part of the mesogenic epoxy monomer does not react and remains as a monomer Although there may be, it is preferable that a part of mesogenic epoxy monomer remains in the state of a monomer without reacting from a heat resistant viewpoint mentioned later.

If it is a small scale, the synthesis|combination of a specific epoxy compound can be performed using reaction containers, such as a flask and a synthesis kiln, if it is a large scale. The specific synthesis method is as follows, for example.

First, a mesogenic epoxy monomer is thrown into a reaction container, a solvent is put if needed, it heats to reaction temperature with an oil bath or a heat medium, and melt|dissolves a mesogenic epoxy monomer. An aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer is added thereto, and then, if necessary, a reaction catalyst is added thereto to start the reaction. Next, a specific epoxy compound is obtained by distilling off a solvent under reduced pressure as needed.

The reaction temperature is not particularly limited as long as the reaction between the epoxy group of the mesogenic epoxy monomer and the functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer proceeds, for example, it is in the range of 100°C to 180°C. It is preferable, and it is more preferable that it is the range of 100 degreeC - 150 degreeC. By setting the reaction temperature to 100°C or higher, the time until the reaction is completed tends to be shorter. On the other hand, by setting the reaction temperature to 180°C or lower, the possibility of gelation tends to be reduced.

The mixing ratio of the mesogenic epoxy monomer and the aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer is not particularly limited. For example, the ratio (A:B) of the number of equivalents of the epoxy group (A) to the number of equivalents (B) of the functional group capable of reacting with the epoxy group (A:B) may be a compounding ratio in the range of 10:10 to 10:0.01. From the viewpoint of fracture toughness and heat resistance of the cured product, a blending ratio in which A:B is in the range of 10:5 to 10:0.1 is preferable.

From the viewpoint of handleability of the epoxy resin, the ratio (A:B) of the number of equivalents of the epoxy group (A) to the number of equivalents (B) of the functional group capable of reacting with the epoxy group (A:B) is in the range of 10:1.6 to 10:3.0. is preferable, the compounding ratio in the range of 10:1.8 to 10:2.9 is more preferable, and the compounding ratio in the range of 10:2.0 to 10:2.8 is still more preferable.

The structure of the specific epoxy compound is, for example, the molecular weight of the specific epoxy compound estimated to be obtained by the reaction of the mesogenic epoxy monomer used for synthesis and the aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer. It can be determined by contrasting the molecular weight of the target compound with the liquid chromatography carried out using a liquid chromatograph equipped with UV and mass spectrum detectors.

Liquid chromatography, for example, uses "LaChrom II C18" manufactured by Hitachi, Ltd. as an analytical column, a gradient method is used, and the mixing ratio (volume basis) of the eluent is determined. Acetonitrile/tetrahydrofuran/10 mmol/l ammonium acetate aqueous solution = 20/5/75 through acetonitrile/tetrahydrofuran = 80/20 (20 minutes from the start) to acetonitrile/tetrahydrofuran = 50/50 (starting) 35 minutes) and continuously change the measurement. Moreover, it carries out by making the flow rate 1.0 ml/min. The UV spectrum detector detects absorbance at a wavelength of 280 nm, and the mass spectrum detector detects the ionization voltage as 2700 V.

The weight average molecular weight (Mw) of the epoxy resin is not particularly limited. From the viewpoint of reducing the viscosity, the weight average molecular weight (Mw) of the epoxy resin is preferably selected from the range of 800 to 1300.

In the present disclosure, the number average molecular weight (Mn) and the weight average molecular weight (Mw) of the epoxy resin are values obtained by liquid chromatography.

Liquid chromatography is performed at a sample concentration of 0.5% by mass, using tetrahydrofuran as a mobile phase, and a flow rate of 1.0 ml/min. A calibration curve is prepared using a polystyrene standard sample, and Mn and Mw are measured in terms of polystyrene using this.

The measurement can be performed using, for example, a high-performance liquid chromatograph "L6000" manufactured by Hitachi Corporation, and a data analysis apparatus "C-R4A" manufactured by Shimadzu Corporation. . As a column, "G2000HXL" and "G3000HXL" which are GPC columns manufactured by Tosoh Corporation can be used, for example.

The epoxy equivalent of the epoxy resin is not particularly limited. From a viewpoint of making the fluidity|liquidity of an epoxy resin and the thermal conductivity of hardened|cured material compatible, it is preferable that it is 245 g/eq - 360 g/eq, It is more preferable that it is 250 g/eq - 355 g/eq, It is still more preferable that it is 260 g/eq - 350 g/eq. do. When the epoxy equivalent of the epoxy resin is 245 g/eq or more, the crystallinity of the epoxy resin does not become too high, and therefore the fluidity of the epoxy resin tends to be difficult to decrease easily. On the other hand, if the epoxy equivalent of the epoxy resin is 360 g/eq or less, since the crosslinking density of the epoxy resin is less likely to decrease, the thermal conductivity of the molded product tends to increase. In the present disclosure, the epoxy equivalent of the epoxy resin is measured by a perchloric acid titration method.

It is preferable that the epoxy resin of this indication contains both a specific epoxy compound and a mesogenic epoxy monomer. When a specific epoxy compound and a mesogenic epoxy monomer are present in an appropriate ratio in the epoxy resin, the crosslinking density at the time of curing can be made higher, and a cured epoxy resin product having better heat resistance tends to be obtained. The ratio of the specific epoxy compound and the mesogenic epoxy monomer present in the epoxy resin can be adjusted depending on the mixing ratio of the mesogenic epoxy monomer and the aromatic compound having a functional group capable of reacting with the epoxy group of the mesogenic epoxy monomer and other reaction conditions. .

<Epoxy resin composition>

The epoxy resin composition of the present disclosure includes the above-described epoxy resin and a curing agent.

(hardener)

The curing agent is not particularly limited as long as it is a compound capable of causing a curing reaction with an epoxy resin. Specific examples of the curing agent include an amine curing agent, a phenol curing agent, an acid anhydride curing agent, a polymercaptan curing agent, a polyaminoamide curing agent, an isocyanate curing agent, and a blocked isocyanate curing agent. A hardening|curing agent may be used individually by 1 type, and may use 2 or more types together.

From the viewpoint of forming a higher-order structure in the cured product of the epoxy resin composition, the curing agent is preferably an amine curing agent or a phenol curing agent, more preferably an amine curing agent, and a compound having two or more amino groups directly bonded to the aromatic ring. more preferably.

Specifically as the amine curing agent, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether , 4,4'-diamino-3,3'-dimethoxybiphenyl, 4,4'-diaminophenylbenzoate, 1,5-diaminonaphthalene, 1,3-diaminonaphthalene, 1,4- diaminonaphthalene, 1,8-diaminonaphthalene, 1,3-diaminobenzene, 1,4-diaminobenzene, 4,4'-diaminobenzanilide, trimethylene-bis-4-aminobenzoate, etc. for example.

From the viewpoint of forming a smectic structure in the cured product of the epoxy resin composition, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3-diaminobenzene, 1,4-dia Minobenzene, 4,4'-diaminobenzanilide, 1,5-diaminonaphthalene, 4,4'-diaminodiphenylmethane and trimethylene-bis-4-aminobenzoate are preferred, and have low water absorption and high water absorption. 3,3'-diaminodiphenylsulfone is more preferable from a viewpoint of obtaining a hardened|cured material of fracture toughness.

Examples of the phenol curing agent include a low molecular weight phenol compound and a phenol novolac resin obtained by linking a low molecular weight phenol compound with a methylene chain or the like to form a novolak. Examples of the low molecular weight phenol compound include monofunctional phenol compounds such as phenol, o-cresol, m-cresol and p-cresol, bifunctional phenol compounds such as catechol, resorcinol and hydroquinone, 1,2,3-trihydroxy and trifunctional phenol compounds such as benzene, 1,2,4-trihydroxybenzene and 1,3,5-trihydroxybenzene.

Content of the hardening|curing agent in an epoxy resin composition is not specifically limited. From the viewpoint of the efficiency of the curing reaction, the ratio of the number of equivalents of functional groups of the curing agent contained in the epoxy resin composition to the number of equivalents of epoxy groups of the epoxy resin (the number of equivalents of functional groups / number of equivalents of epoxy groups) is preferably in an amount of 0.3 to 3.0, , more preferably 0.5 to 2.0.

(Other ingredients)

The epoxy resin composition may contain other components other than an epoxy resin and a hardening|curing agent as needed. For example, a curing catalyst, a filler, etc. may be included. As a specific example of a curing catalyst, the compound illustrated as a reaction catalyst which can be used for the synthesis|combination of a multimer is mentioned.

(purpose)

Although the use in particular of an epoxy resin composition is not restrict|limited, It can use suitably also for the processing method which is low in viscosity and requires that it is excellent in fluidity|liquidity. For example, it can be preferably used also for the production of FRP involving a step of impregnating the epoxy resin composition while heating the voids between the fibers, and for the production of a sheet-like article involving a step of spreading the epoxy resin composition with a squeegee while heating it. have.

The epoxy resin composition of the present disclosure is a processing method in which it is desired to omit or reduce the addition of a solvent for lowering the viscosity from the viewpoint of suppressing the generation of voids in the cured product (for example, production of FRP used in aircraft, spacecraft, etc.) can also be preferably used.

<Cured epoxy resin material and composite material>

The cured epoxy resin product of the present disclosure is obtained by curing the epoxy resin composition of the present disclosure. The composite material of the present disclosure includes the cured epoxy resin material of the present disclosure and a reinforcing material.

The material of the reinforcing material included in the composite material is not particularly limited, and may be selected depending on the use of the composite material. Specific examples of the reinforcing material include carbon materials, glass, aromatic polyamide-based resins (eg, Kevlar (registered trademark)), ultra-high molecular weight polyethylene, alumina, boron nitride, aluminum nitride, mica, silicone, and the like. The shape of is not particularly limited, and examples thereof include fibrous (狀), particulate (filler), etc. From the viewpoint of strength of the composite material, the reinforcing material is preferably a carbon material, and more preferably a carbon fiber. The number of reinforcing materials contained in the composite material may be one, or two or more types may be sufficient as them.

[Example]

Hereinafter, although the said embodiment is demonstrated more concretely based on an Example, the said embodiment is not limited to these. In addition, "part" and "%" are a mass basis unless it specifically limits.

(Synthesis of Epoxy Resin 1)

In a 500 ml three-necked flask, (4-{4-(2,3-epoxypropoxy)phenyl}cyclohexyl=4-(2,3-epoxypropoxy)benzoate, the following structure) as a mesogenic epoxy monomer was added 50 g was weighed, and 80 g of propylene glycol monomethyl ether was added there. A cooling tube and a nitrogen inlet tube were installed in the three-necked flask, and a stirring blade was attached so as to be immersed in a solvent. This 3-neck flask was immersed in a 120 degreeC oil bath, and stirring was started. After confirming that the epoxy monomer was dissolved and became a transparent solution, 5.2 g of 4,4-biphenol as a specific aromatic compound and 0.5 g of triphenylphosphine as a reaction catalyst were added, followed by heating at an oil bath temperature of 120 ° C. continued. After continuing heating for 3 hours, propylene glycol monomethyl ether is distilled off from the reaction solution under reduced pressure, and the residue is cooled to room temperature (25° C.), whereby a part of the mesogenic epoxy monomer reacts with a specific aromatic compound, and the epoxy compound B Epoxy resin 1 in the state of was obtained.

(Synthesis of Epoxy Resin 2)

In the same manner as for epoxy resin 1, except that 3.1 g of hydroquinone was added instead of 5.2 g of 4,4-biphenol, a part of the mesogenic epoxy monomer reacted with a specific aromatic compound to form epoxy resin 2 in the state of epoxy compound A got it

(Synthesis of Epoxy Resin 3)

Except for adding 3.1 g of resorcinol instead of 5.2 g of 4,4-biphenol, the same procedure as for epoxy resin 1 was carried out, and a part of mesogenic epoxy monomer reacted with a specific aromatic compound to form epoxy compound A. Epoxy resin 3 got

(Pre-treatment of curing agent)

160 g of 3,3-diaminodiphenylsulfone (Wako Pure Chemical Industries, Ltd.) was used at a pressure of 0.15 using a nanojetmizer NJ-50-B manufactured by Aisin Nanotechnology, Ltd. It grind|pulverized at MPa and the processing amount of 240 g/hr, and obtained 155g of fine powders with an average particle diameter of 8 micrometers. The obtained fine powder was used in the following examples and comparative examples.

<Example 1>

35.0 g of epoxy resin 1 and 15.0 g of epoxy resin 2 were weighed in a plastic container, put into a thermostat, and heated to 90°C. Then, 9.5 g of 3, 3- diamino diphenyl sulfone was added, and it stirred with the spatula for 1 minute. Next, using an autorotation/revolution mixer, it stirred under the conditions of 1600 rotations/min (rpm) and 30 min, and obtained the epoxy resin composition. The obtained epoxy resin composition was transferred to a stainless steel petri dish in which the inner wall was subjected to a mold release treatment, put into a constant temperature bath, and heated at 150° C. for 4 hours to harden the epoxy resin composition. After cooling to room temperature (25°C), the cured epoxy resin material was taken out from the stainless steel petri dish, cut out into a 3.75 mm × 7.5 mm × 33 mm rectangular parallelepiped, to prepare a test piece for fracture toughness evaluation. Furthermore, the cured epoxy resin material was cut out into a rectangular parallelepiped of 2 mm x 0.5 mm x 40 mm, and the test piece for glass transition temperature evaluation was produced.

<Example 2>

25.0 g of epoxy resin 1, 25.0 g of epoxy resin 2, and 9.6 g of 3,3-diaminodiphenylsulfone were carried out in the same manner as in Example 1 to obtain an epoxy resin composition and a cured epoxy resin. Using the obtained cured epoxy resin, a sample for evaluation of fracture toughness and glass transition temperature was prepared in the same manner as in Example 1.

<Example 3>

In the same manner as in Example 1, except that 35.0 g of epoxy resin 1, 15.0 g of epoxy resin 3 instead of epoxy resin 2, and 9.7 g of 3,3-diaminodiphenylsulfone were weighed, the epoxy resin composition and the cured epoxy resin product got Using the obtained cured epoxy resin product, a sample for evaluation of fracture toughness and glass transition temperature was prepared in the same manner as in Example 1.

<Example 4>

45.0 g of epoxy resin 1, 5.0 g of epoxy resin 2, and 9.5 g of 3,3-diaminodiphenyl sulfone were carried out in the same manner as in Example 1 to obtain an epoxy resin composition and a cured epoxy resin. Using the obtained cured epoxy resin product, a sample for evaluation of fracture toughness and glass transition temperature was prepared in the same manner as in Example 1.

<Example 5>

16.7 g of epoxy resin 1, 33.3 g of epoxy resin 2, and 9.7 g of 3,3-diaminodiphenylsulfone were carried out in the same manner as in Example 1 to obtain an epoxy resin composition and a cured epoxy resin. Using the obtained cured epoxy resin product, a sample for evaluation of fracture toughness and glass transition temperature was prepared in the same manner as in Example 1.

<Comparative Example 1>

50.0 g of epoxy resin 1 and 9.4 g of 3,3-diaminodiphenyl sulfone were weighed in a stainless steel petri dish in the same manner as in Example 1 to obtain an epoxy resin composition and a cured epoxy resin product. Using the obtained cured epoxy resin product, a sample for evaluation of fracture toughness and glass transition temperature was prepared in the same manner as in Example 1.

<Comparative Example 2>

50.0 g of epoxy resin 2 and 9.8 g of 3,3-diaminodiphenyl sulfone were weighed in a stainless steel petri dish in the same manner as in Example 1 to obtain an epoxy resin composition and a cured epoxy resin product. Using the obtained cured epoxy resin product, a sample for evaluation of fracture toughness and glass transition temperature was prepared in the same manner as in Example 1.

[Measurement of dynamic shear viscosity]

As an index of the viscosity stability of the epoxy resin composition, the dynamic shear viscosity under high shear (Pa·s) was used. The dynamic shear viscosity of the epoxy resin composition was measured with a parallel plate vibration rheometer. Measurement conditions were a frequency of 1 Hz and a strain of 1000%. MCR-301 (Antonpa Corporation) was used for the evaluation apparatus.

In the measurement, the epoxy resin composition was allowed to stand for 3 minutes or longer on a stage heated to 90°C and melted, and then a parallel plate having a diameter of 12 mm was lowered so as to have a gap of 0.2 mm. Next, the device stage temperature was lowered to 80°C, and measurement was started. After raising the temperature to 90°C for the first 5 minutes, the temperature was maintained at 90°C. The viscosity (initial viscosity) after 10 minutes from the start of the measurement (after 5 minutes by holding at 90°C) and the viscosity after 2 hours (after 1 hour and 55 minutes by holding at 90°C) from the start of the measurement were measured. Moreover, the thickening rate defined by the following formula was calculated|required.

Viscosity after thickening rate = 2h/initial viscosity

[Measurement of fracture toughness value]

As an index of the fracture toughness of the cured epoxy resin product, a fracture toughness value (MPa·m ^1/2 ) was used. The fracture toughness value of the test piece was calculated by performing three-point bending measurement based on ASTM D5045. Instron 5948 (Instron Corporation) was used for the evaluation apparatus.

[Evaluation of dynamic viscoelasticity]

As an index of the heat resistance of the cured epoxy resin product, the glass transition temperature (Tg) was used. The glass transition temperature of the test piece was calculated by performing dynamic viscoelasticity measurement in a tensile mode. Measurement conditions were a frequency of 10 Hz, a temperature increase rate of 5°C/min, and a strain of 0.1%. In the obtained temperature-tan δ relationship diagram, the temperature at which tan δ becomes the maximum was regarded as the glass transition temperature. As the evaluation apparatus, RSA-G2 (manufactured by TA Instruments) was used.

[X-ray diffraction measurement]

In order to confirm the presence or absence of formation of a higher-order structure (smectic structure) in the cured epoxy resin product, X-ray diffraction measurement was performed. The measurement conditions were a tube voltage of 50 kV, a tube current of 300 mA, a scanning speed of 1°/min, and a measurement angle of 2θ = 2° to 0° using CuKα radiation. As the evaluation apparatus, an X-ray diffraction apparatus manufactured by Sharikaku Co., Ltd. was used. When a peak was detected in the range of 2θ = 2° to 0°, it was judged that a smectic structure was formed.

Table 1 shows the initial viscosity at 90° C., the viscosity and the thickening rate after 2 hours for the epoxy resin compositions of Examples 1 to 5 and Comparative Examples 1 and 2. In addition, the fracture toughness values, the glass transition temperature (Tg) and the presence or absence of the smectic structure of the cured epoxy resins of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Table 1.

[Table 1]

As shown in Table 1. The epoxy resin compositions of Examples 1 to 5 containing both epoxy compound A (epoxy resin 2) and epoxy compound B (epoxy resin 1) as an epoxy resin have an initial viscosity when a large shear strain of 1000% is applied. It was sufficiently low, and the increase in viscosity after 2 hours was also suppressed, and good viscosity stability was exhibited. In addition, the cured epoxy resin obtained from these epoxy resin compositions exhibits excellent fracture toughness and heat resistance.

The epoxy resin composition of Comparative Example 1 in which the epoxy resin contains the epoxy compound B but does not contain the epoxy compound A has a low initial viscosity, but after 2 hours from the start of the measurement, the viscosity increases to 16 times or more, In application|coating, the film thickness was not controllable, and it was a level where application|coating was difficult.

Similarly, the epoxy resin composition of Comparative Example 2 in which the epoxy resin contains the epoxy compound A but does not contain the epoxy compound B also increases the viscosity remarkably after 2 hours from the measurement, and is applied without a solvent in terms of film thickness control and fluidity. was a difficult level.

Claims (7)

It contains an epoxy compound A having two or more mesogen structures and one or more phenylene groups, and an epoxy compound B having two or more mesogen structures and one or more divalent biphenyl groups,
Among the two or more mesogenic structures that at least one of the epoxy compound A and the epoxy compound B has, at least one is a mesogenic structure represented by the following general formula (3), an epoxy resin:

(In the formula (3), R ³ to R ⁶ each independently represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms). The method of claim 1,
At least one of the said epoxy compound A and the said epoxy compound B has a structure in the state in which one said phenylene group or the said bivalent biphenyl group is arrange|positioned between two said mesogenic structures, The epoxy resin. The epoxy resin composition containing the epoxy resin of Claim 1 or 2, and a hardening|curing agent. 4. The method of claim 3,
An epoxy resin composition capable of forming a smectic structure when cured. A cured epoxy resin product, which is a cured product of the epoxy resin composition according to claim 3 . A composite material comprising the cured epoxy resin according to claim 5 and a reinforcing material.
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